1. Field
The following description relates to a method and apparatus for detecting an intended packet by a sliding intermediate frequency (SIF) non-coherent (NC) ultra low power (ULP) wireless receiver.
2. Description of Related Art
The ultra-low-power (ULP) wireless communication is gaining importance with the advent of Internet of Things (IoT), wearables and e-Health applications. In general, a ULP transceiver has low data rates, for example, 1 Mbps, and operates over short distances, for example, distances less than 50 meters (m). Existing ULP transceivers achieve power consumption of 1 nanojoule per bit (nJ/bit), which has led to the evolution of standards like IEEE 802.15.4q and Bluetooth Low Energy (BLE).
A radio frequency integrated circuit (RFIC) is a dominant power consuming block in ULP wireless communication. In order to extract maximum power savings from the RFIC, On-Off keying (OOK) has been developed as baseband (BB) modulation technique in the IEEE 802.15.4q standard. OOK BB modulation not only provides inherent modulation duty cycling at a transmitter power amplifier, but also leads to relaxed requirements on RFIC components such as a frequency synthesizer and a phase locked loop (PLL). Further, OOK enables a non-coherent (NC) receiver design, and thus obviates the need for phase synchronization.
Direct current offset (DCO) is a problem in sliding intermediate frequency (SIF) ULP receivers when gains of BB stages are high. Even small magnitudes of DCO may be significantly amplified due to the high gains. It is therefore important to estimate DCO and design a robust DCO compensation (DCOC) algorithm.
Automatic gain control (AGC) is a crucial feature of the ULP receivers to accommodate a wide dynamic range of received power levels. In absence of AGC, a total gain is fixed, which leads to either saturation effects or a low signal-to-noise ratio (SNR) at outputs of an analog-to-digital converter (ADC). In either case, a signal is not demodulated properly. Moreover, the performance of AGC may be affected by DCO.
IEEE 802.15.4q compliant ULP chipsets are expected to be deployed in e-Health and sensor applications, where the signal traffic is sparse and has a low duty cycle. Hence, a duration of a noise interval preceding an 802.15.4q PHY packet may be quite long. Thus, it is important to design an energy detection (ED) algorithm to declare a transition from a noise period to a signal period with a high reliability. Further, the ULP chipsets operate in an unlicensed 2.4 gigahertz (GHz) industrial scientific medical (ISM) band, coexisting with wireless local area network (WLAN) devices, Bluetooth (BT) and Bluetooth Low Energy (BLE) devices. Accordingly, there is a need to design a packet detection (PD) method that may reliably distinguish between 802.15.4q physical layer packets and other physical layer packets in the ISM band.